Slow but sure seems to be working for the supporters of the Senate’s immigration bill. With Washington distracted by scandals large and small, the Senate Judiciary Committee continued to chew its way through amendments to the bipartisan measure on Monday. With 10 Democratic supporters and two Republican authors of the bill on the 18-member panel, the committee has parried dozens of attempts to undermine the measure during the first four days of debate, such as a Republican proposal on Monday that would have allowed profiling of immigrants based on their country of origin.

Working through the first half of the 300 amendments (the full list, with available results, can be viewed here) has been a laborious process, but in many respects a model one. The transparent method adopted by the committee, led by Democratic chairman Patrick Leahy, has led to civil debate and minimal demagoguery. Some two dozen amendments filed by Republicans have been adopted. Many of them address conservatives’ concerns about border security, including a Monday proposal from Utah Republican Orrin Hatch — seen as a swing vote on the bill — that would create a new biometric ID system at the 30 most trafficked U.S. airports. Democrats like New York’s Chuck Schumer supported Hatch’s amendment as part of an effort to ease concerns about the bill’s enforcement provisions, as well as insulate it from charges of partisanship.

But the Senators trying to pass the first major overhaul of U.S. immigration law in a generation have slogged only through the easy part. The committee has yet to consider several amendments whose passage could unravel fragile alliances. One of these is Hatch’s effort to boost the allotted number of high-skilled visas. The idea, championed by a contingent of Silicon Valley tech companies, is opposed by labor groups, who say it would threaten the job prospects of American workers. The panel may also take up Leahy’s amendment to allow gays to sponsor their foreign partners for green cards. If adopted, that change could create fissures within the so far sturdy Gang of Eight, whose Republican members ardently oppose it. Many Democrats, including those who support Leahy’s amendment, are hoping he will withhold it until the bill reaches the full Senate, where it would presumably be defeated without scuttling the entire bill. The Judiciary Committee is hoping to wrap up its work as early as Wednesday night.